The fares are almost always enticing. Phoenix to Las Vegas as low as $40 one-way. Atlanta to Fort Lauderdale for $54. Denver to New York City, $74. All on nonstop flights.

Discounters Spirit, Frontier and Allegiant – ultra-low-cost carriers in airline industry lingo – have long known how to grab travelers' attention.

The bare-bones ticket prices, of course, don't come with much. Travelers pay extra for almost everything. The airlines used to bury the fine print on their fees but now trumpet their lack of frills as major airlines are gradually switching to the a la carte approach.

That doesn't mean travelers are paying attention. The airlines draw plenty of social media ire from passengers unaware of their policies.

For newbies, here's a traveler's guide to flying Spirit, Frontier and Allegiant

1. The ticket price only gets you a seat on the plane. And we don’t mean an assigned seat – for free, at least. Spirit Airlines spells it out on its website: "A ticket with us gets you and a personal item from A to B." The airlines charge for seat assignments, checked and carry-on bags, and snacks and drinks, including water.

2. Bags don’t fly free, even carry-on bags. Passengers are allowed one free personal item that fits under the seat, such as a backpack or purse or laptop bag. The airlines closely monitor the size of those carry-ons. Want to bring a standard carry-on bag to put in the overhead bin? You’ll pay. Carry-on bag fees vary by carrier and when you pay for the carry on. (See No. 6 below.) Frontier’s prices start at $35 each way, Spirit’s at $35, Allegiant’s at $18. Note that Spirit and Frontier’s carry-on fees are higher than their checked-bag fees, so check the bag unless you refuse to hassle with baggage claim. Spirit and Frontier's carry-on bag fee includes priority boarding.

3. Unlike major airlines, most of which now charge $30 for the first checked bag and $40 for the second, the discounters’ checked-baggage fees vary by when you pay for the bags and, in some cases, the route and time of year. Want to check one bag on Frontier? That’ll be $30one way if you pay when you book your ticket online, $38 if you pay after you book your ticket but before online check-in, $40 if you pay during online check-in or through the reservation center, and $50at the airport ticket counter or kiosk. Spirit's bag pricing is dynamic and can have travelers paying one price for a bag on the flight out and a different price on the flight back. The general price range for one checked bag on Spirit: $31-$37 during online booking, $41-$45 before and during online check in; and $52 at the airport ticket counter or through reservations. On Allegiant, travelers will pay $25-$30for the first checked bag during online booking, $45after booking but before they get to the airport and $50at the airport. Bottom line: Pay for your bags when you book your ticket.

The airlines have so many different bag prices, Allegiant and Spirit have online baggage fee calculators, and the airlines' fee tables have more lines than an income tax form.

4.Don't over-stuff your bags. The weight limit for checked bags on Spirit and Allegiant is 40 pounds, not the standard 50 pounds allowed at major airlines and Frontier. Overweight bag charges apply in all cases.

5. Whatever you do, DON’T bring a bag to the gate in an attempt to dodge bag fees. This might work on major airlines, which often ask for volunteers to check their bags for free on full flights where overhead bin space is bound to fill up. Spirit, Frontier and Allegiant charge hefty surcharges to check bags at the gate. It’ll cost you $62 on Spirit, $60 on Frontier and $50 on Allegiant If you plan to bring a carry-on, pay for it when you book your ticket.

6.Want to snag discount airlines’ lowest fares? On Frontier and Spirit, join the club. Frontier’s Discount Den membership is $60 a year and it gets you discounts for up to six people per reservation. As with airfares, savings vary by route, travel dates, flight time and other factors. On a one-way, nonstop flight from Denver to Washington, D.C., in mid-July, the Discount Den fare was $10 lower than the standard fare.

Spirit offers the $9 Fare Club, which is $60 per year and covers up to nine passengers on the same reservation. In addition to fare discounts, $9 Fare Club members pay less for bags. On a flight from Chicago to Fort Myers, Florida, for example, the carry-on bag fee is $28 versus the normal $37, and a checked bag is $23 versus the normal $32, if paid when booking the ticket.

7. Want to save more money? Buy your ticket at the airport. Yes, the airport. Unlike major airlines, Allegiant, Spirit and Frontier have a usage fee for booking tickets online or through the reservations center. Allegiant charges $18, Spirit, $9-$21, and Frontier charges $19. The fees are each way and are included in the fares listed on their websites.

What's not listed: an additional usage charge for travelers who call their reservation centers. Allegiant's call center fee is $15 each way per ticket, Frontier charges $10 per booking and Spirit charges $35 per booking.

Airport ticket hours are limited and vary by airport. Also, read the fine print of fare sales because some sales only include tickets booked online, so it would be a waste of time to go to the airport. Lastly, never wait until the day of your trip to buy a ticket at the airport (on any platform) because last-minute fares are generally airlines' highest fares.

8. Picky about your seat or must sit with your family or other traveling companions? Then pay to reserve one in advance. There are no free advance seat assignments as there are on major airlines (though the number of free seats available on those airlines is shrinking). In addition to reserving standard seats, Frontier and Spirit also sell seats with extra legroom. Passengers who don't pay for a seat assignment will be assigned open seats at check-in.

9. Don't want to be nickel-and-dimed? Frontier and Spirit sell a package of perks you can add on to your ticket price. Frontier has the Works bundle and the Perks bundle, which includes a carry-on bag, checked bag, assigned seat and priority boarding. The works bundle also includes a couple extra perks, including ticket refunds. For a Denver-Nashville trip in June, the "perks'' package was an extra $140 round trip on a $237 ticket, the "works'' package, an extra $150 round trip. Spirit sells the "Thrills Combo,'' which includes a checked bag (up to 50 pounds instead of the usual 40 pounds), a carry-on bag, seat selection and more. The price for the Thrills on a sample Chicago-Fort Lauderdale, Florida, flight: $75 each way. Prices vary by airline and flight, so do the math to see if it saves you money over buying bags, seats and other "perks" separately.

10. Print your own boarding pass. Spirit and Allegiant charge to print boarding passes at the airport. Spirit charges $2 to print a boarding pass at an airport kiosk and $10 if an agent has to do it. Allegiant charges $5 per boarding pass printed by an airport agent at select airports. (The airline doesn't have kiosks.)

11.Beware of limited rebooking options if your flight is canceled or delayed. The discounters don't have as many daily flights to destinations as their larger rivals and don't have agreements to transfer stranded passengers to other airlines. Allegiant passengers are the most vulnerable as the vacation airline offers one daily flight a few times a week on most routes. If your Rockford, Illinois, to Las Vegas flight is canceled for weather or mechanical reasons, for example, the earliest you will get out is the next day.

Posted!

A link has been posted to your Facebook feed.

Goa, India: Located along India’s western coast, this small state borders the Arabian Sea and is separated into North and South Goa. You can fly directly into Goa from New Delhi in under three hours for about $50 one-way. Flights are cheap from major U.S. cities like Chicago and Boston, thanks to budget airline WOW Air’s latest route to New Delhi. Once a Portuguese colony, Goa offers a broad mix of cultures and landscapes; get ready to discover small, local villages, popular beaches, flea markets, ancient temples, 17th-century churches and a variety of cuisines. Getty Images/iStockphoto

Phu Quoc Island, Vietnam
Accessible via a short and inexpensive flight from Ho Chi Minh City (Saigon), Phu Quoc is a picturesque island paradise. While getting to Southeast Asia isn’t “cheap,” it’s currently reasonably affordable to fly to Ho Chi Minh City, with round-trip flights hovering around $800 from New York City, Boston, Chicago and Los Angeles. The island is located off the Mekong Delta and still has some untouched beaches and affordable luxury resorts, making this tropical destination a great value getaway. It’s also deemed a “Special Economic Zone” so visitors don’t need a visa if they’re only staying here. Getty Images/iStockphoto

Curacao: This Dutch island is located in the southern part of the Caribbean and is best known as a hot spot for European and Canadian travelers, but there are direct, inexpensive routes from U.S. hubs like New York City and Miami, too. Curacao is one of the best diving spots in the Caribbean and has cheaper hotels than the other nearby islands like Aruba. You’ll be more than impressed with the color of the water, as well as by the affordable prices at hip restaurants and bars in the Pietermaai area. Getty Images/iStockphoto

Hawaii: Airfare to Hawaii was cheap for much of 2018, and trends suggest these more affordable prices could continue well into 2019, especially if fuel prices stay low. Southwest is expected to start selling fares from the West Coast any day now, and Hawaiian Airlines will sell basic economy fares starting this year. To minimize on-the-ground costs, book a hotel that is close to (rather than right on) the beach; and for dining out, opt to visit local poke joints instead of expensive resorts. Art Wager, Getty Images

Guanacaste, Costa Rica: Head to the Pacific Coast of Costa Rica for some pura vida. The country’s Guanacaste province makes for a cheap tropical vacation this year thanks to its value-priced hotels and affordable on-the-ground costs. The family-friendly beach area is ideal for relaxing, but it’s also close to some of the country’s natural tourist attractions like national parks, volcanoes and waterfalls. Fly into nearby Liberia, whose airport offers direct and reasonably priced flights from U.S. cities like Los Angeles, Houston and New York City. Getty Images

Samana, Dominican Republic: This newer resort area in the Dominican Republic ranks among the cheapest Caribbean spots this year on the Price of Travel Index. With its own airport (built in 2006) and direct routes from Montreal and Toronto, this is a hidden gem of the Caribbean. Uncrowded beaches, whale watching and a national park give this region a well-balanced mix of tropical vacation activities. Visit this year while it’s still relatively quiet and prices are cheap. Getty Images/iStockphoto

Quintana Roo, Mexico: The Mexican state of Quintana Roo includes tourist areas like Cancun, Playa del Carmen, the Riviera Maya, Tulum, Isla Mujeres, Isla Holbox and Cozumel. With affordable airfares, a strong dollar against the peso, cheap hotel prices thanks to competition, and a wide variety of all-inclusive resort packages that appeal to all ages of travelers, this state is guaranteed to be a fun and cheap tropical getaway. Cancun International Airport is an easy gateway to the region. Beyond Cancun, each town and city offers bucket-list activities with its own distinctive vibe — after all, where else can you swim in a cenote, visit ancient Maya ruins and lounge on the beach all in one day? Jonathan Ross, Getty Images/iStockphoto

Placencia, Belize: This fishing village is found on Belize’s southeastern side, away from the more popular tourist destinations in the country. While it’s a little more difficult to get to — about 160 miles from Belize City — here you’ll find a 16-mile coastline that includes some of the best beaches in the country. There’s also snorkeling, diving and fishing, as well as a natural reserve on the mainland and a “barefoot-friendly” town with shops, seafood restaurants and cafes. You can fly directly to the peninsula; however, there’s also a less-expensive shuttle service you can take from Belize City. Getty Images/iStockphoto

Negril, Jamaica: In Negril, about an hour and a half from Montego Bay, you’ll find cheap hotels and a mix of upscale, unique lodging options. You’ll also find coral reefs and Seven Mile Beach. What you won’t find are the kind of over-crowded and expensive all-inclusives that are so popular in Montego Bay. You’ll still want to fly into the Montego Bay — one of the largest and busiest airports in the Caribbean — since direct and inexpensive flights are easy to find from major U.S. hubs. Getty Images/iStockphoto

Bimini, the Bahamas: With nonstop flights for about $100 round trip from the East Coast to Fort Lauderdale and Miami, you can easily reach the two main islands of Bimini, which also happen to be the closest entry point to the Bahamas from the U.S. — just 50 miles from Florida’s coast. Charter flights from Fort Lauderdale and Miami can be more expensive, so instead opt for the daily, two-hour ferry that leaves the Port of Miami. Once on Bimini, enjoy pristine beaches and fascinating history — Ernest Hemingway, Martin Luther King, Jr. and Jimmy Buffet all have a connection to this small part of the Bahamas. Getty Images/iStockphoto